Power lift



July 2, 1946. w, H, WORTHINGTON v 2,403,422

POWER LIFT Filed Aug. 6, 1942 6 Sheets-Sheet l g, w LL C) N"*4\ j j co 1m Z i at n LU3 n 'XE :0 Q j; z z

. k h. .0 3 Q m INVENTOR WAYNE T y ,v 1946- w. H. WORTHINGTON 2,403,422

- POWER LIFT Filed Aug. 6, 1942 6 sheefisshet 2 INVENTOR WAYNE H.WORTHINGTON POWER pm Filed Aug. 6, 1942 6 Shets-Sheet 5 INVENTOR y 1946-W. H. WORTHINGTON, 2,403,422

POWER LIFT Filed Aug. 6, 1942 6 Sheets-Sheet 6 FIG ,9

309 m \1\ I76 Vrl FIG. IO

Patented juiy 2, it

uNirEn stares rear orric Wayne El. Worthington, Waterloo, llowa,assignor to John Deere Tractor Company, Waterloo, Iowa, a corporation oiIiowa Application August 6, 1942, Serial No. d53,9.07

14 Claims.

This application i a continuation in part f my co-pending application,Serial No. 414,631, filed October 11, 1941, and now abandoned.

The present invention relates generally to power lift mechanism foragricultural tractors and the like, and is more particularly concernedwith new and useful improvements in hydraulically operated power liftapparatus carried by a farm tractor and driven by the tractor motor.

The object and general nature'of the present invention is the provisionof a hydraulic lifting mechanism embodying a pair of operating ram unitsderiving operating en'ergy from a single fluid pressure pump; and newand improved control means carried as a compact self-contained unit onthe tractor and including mechanism 4 associated with at least one ofthe ram units whereby movement of the latter may automatically beterminated after a given entent of movement, depending upon the positionof an adjustable part which may be set in different positions. Thus, amechanism of this kind is admirably adapted for use on an agriculturaltractor for the controlof ground working tools in which such adjustmentmechanism may be employed. for determining'the operating depth of thetools.

More specifically, it is a feature. of this invention to provide new andimproved controlmeans I for hydraulic lifting mechanism of the typeincluding a piston and cylinder to which a fluid, preferably oil, issupplied under pressure and controlled by a movable valve member or thelike.

It will be appreciated that when. a connection is established betweenthe valve and the piston whereby movement of the latter to apredetermined position automatically returns the'valve to a neutralposition, the movement of the piston after it has engaged the controlvalve and started to close the same becomes progressively slower, sincethe valve is moved toward its closed position the flow of fluid to thecylinder likewise is reduced, thus slowing down the movement of thepiston, and this in turn causes even slower movement of the valve. It isevident that the last part of the piston movement becomes very slowindeed, at which time the valve is barely cracked open to admit a smallstream of oil to the cylinder. The action of this small stream of oilunder pressure against the edges of the valve elements deteriorates thelatter by wear,

' and furthermore the slow movement of the. p'is- 2 which will cause thecontrol valve to be moved quickly and positively from its open to itsclosed position and thus to stop the movement of the hydraulic pistonmore abruptly.

This object has already been accomplished by providing a spring foractuating the valve element, the spring being energized manually throughthe manual control lever of the valve, whereupon the piston releases atrigger device which permits the spring to shift the valve to closedposition. With this arrangement, however, the manual control of thevalveis held out of action bythe trigger, thus preventing themanipulation of the manual control lever during the full stroke of thepiston; In other words,

this arrangement provides only for a full stroke operation of thehydraulic piston. A more specific object of myinvention, therefore,relates to the provision of a control devicefor hydraulic mechanism bywhich the sudden cut-oft at the end of the piston stroke is obtained,without sacrifice of the control of the piston at any point within itsrange of movement. Particularly,' it is a feature of the presentinvention in this-connection to provide a pivoted bell crank, adapted tobe engaged by the piston or a movable therewith, with an arm disposedggeperally parallel with respect to a second arm oprative1y connectedwith the hydraulic valve to be closed,

and with a compression spring unitcomiected between said generallyparallel arms, whereby ton as it approaches its terminal position isundesirable from an operating standpoint. Therefore,'it is a feature of.this invention to provide a control device for the hydraulic mechanism,

positive control of the ;,valve is eilected.

Another important feature of the present invention is the provision ofan improved control valve box arrangement particularly accommodating amanual control of the two ram units and enclosing the operating linkageby which the manual control is augmented by an auxiliary controlassociated with one of the-manual controls whereby the associated ramunit is capable-of a variable stroke and may be hydraulicallylocked inany one of a number of positions of adjustment. An arrangement of thiskind is particularly applicable for the control of farm implelift andcontrol mechanism constructed according to the principles of the presentinvention;

Figure 2 is a rear view of the portion of the tractor and power liftshown in Figure 1;

Figure 3 is a view taken generally along the line 3-3 of Figure 1 andlooking rearwardly into the control valve box;

Figure 4 is a fragmentary sectional view taken generally along the line4-4 of Figure 3, showing the biased means that normally holds one, ofthe control valves in a neutral position;

Figures 5 and 6 are sectional views taken, respectively, along the linesI--5 and 6-6 of Figure 3 and looking in the direction of the arrows;

Figures 7 and 8 are sectional views taken generally along the lines 1-1and 8-8, respectively, of Figure 3;

Figure 9 is a sectional view taken along the line 9-3 of Figure 1;

Figure 10 is a fragmentary side view .of the manually shiftable controlhandle, with the member that moves with one of the ram units forautomatically returning the valve handle to a neutral position;

Figure 11 is a detail view, illustrating the mounting of the adjustablemember on the valve control handle shown in Figure 10; and

Figure 12 is a section taken along the line I2-i2 of Figure 11.

generally Referring now to the drawings, more particularly Figures 1 and2, the reference numeral 1 indicates the rear portion of the combinedcrank case and supporting framework of a tractor of well-knownconstruction, and the reference numeral 2 indicates the rear axlehousing of such a tractor. The axle housing 2 comprises laterallydlrected extensions each receiving a drive shaft 5 Journaled therein byany suitable means, and at its inner end each drive shaft carries alarge driving gear 6 actuated by suitable transmission mechanism anddifferential means.

The hydraulic mechanism with which the present invention is moreparticularly concerned in= cludes a unit, indicated in its entirety bythe reference numeral II), which is adapted to be bolted over the 'rearopening ii ofthe axle housing 2, as best shown in Figure 1, the boltsbeing indicated in Figure 2 by the reference numeral I2. The unit lincludes a housing 13 in the upper portion of which is an opening i5,and the upper portion of the housing 13 is formed with right and lefthand lateral housings or sleeve portions I 6 and [1 in which a liftingrockshaft i8 is mounted for rocking movement upon suitable bearingmeans. The lower portion of the housing is formed with a journal 2l'adapted to receive the rear end of a power take-oil shaft 22 driven bysuitable means (not shown) from the tractor' motor. The lower portion ofthe housing 13 also carries a hydraulic pump'25 of the positivedisplacement type, comprising a housing 28 or pump body secured to therear wall 21 of the housing 13, as by bolts 28. The pump gears areindicated at 30 and 31, the latter gear being secured in any suitablemanner to the rear portion of the power take-oil shaft 22, as best shownin Figure l. The housing 13 is formed so as to serve as a sump 33 withwhich the suction side of the pump 25 communicates by means of anopening (not shown). The housing 13 is also formed with an upwardlyextending passage 3|, the lower end of which communicates. with the highprewure side of the gear pump 25. Secured in any manner over the openingl in the forward wall of the housing i3 is a cylinder 35 closed at itsfor A ward end and open at its rear end over the opening I5. Th forwardclosed end of the cylinder 35 communicates with a longitudinally extending passage 36 which at its rear end communicates with a passage 31formed in a longitudinally extending section 40 of the housing H. Apiston 38 is movably mounted within the cylinder 35 and receives apiston rod 33 which at its rear end is pivoted by a pin ll to the lowerend of an arm 42 secured to the generally central portion of the liftingrockshaft l3.

The construction asso far described is substantially the same as thatshown in the prior patent to E. McCormick et all, No. 2,107,760, datedFebruary 8, 1938, to which reference may be made if necessary.

According to the principles of the present invention suitable controlmechanism is provided for controlling the flow of fluid under pressureto and from the pump 25-and not only the cylinder- 35 but also anauxiliary or second cylinder which preferably is mounted exteriorly ofthe tractor. This auxiliary cylinder or ram unit is indicated in itsentirety by the reference numeral 50 and is'shown somewhatdiagrammatically in Figure 3. It will be understood that this cylindermay be connected in any suitable manner to any implement part or othermember which it is desired to control by the valve mechanism, with whichthe present invention is more particularly concerned, that is employedfor also controlling the main cylinder and piston disposed in the rearaxle housing 2. The main piston and cylinder unit or ram unit isindicated in its entirety in Figure 1 by the reference numeral 5|.

The rear wall 21 (Figure 8) of the central housing I3 is provided with arear opening 55 over which a valve or control box, indicated in itsentirety by the reference numeral 56, is adapted to be secured. Thecontrol box 55 includes a casing or housing 51 having means whereby itmay be secured in place over the opening 55, such as by cap screws 58.The front side of the casing 51 is open while the sides and rear andbottom walls are formed with various valve controlled and other passageswhich will now be described.

The bottom wall 61 of the valve casing 51 is provided with an opening 62adjacent the left side (theright side as viewed in Figure 3) and theopening 62' lies at the lower forward end of a generally verticallyextending high pressure passage 63 (Figure 5). The opening 62 isdisposed in such a. position as to communicate with the upper end of thepassage 34 (Figure 1) which leads upwardly from the high pressure sideof the pump 25. As best shown in Figure 5, the passage 63 is formed in athickened portion 64 of the valve casing 51. At the other side of thecasing 51 the lower wall 61 thereof is formed with an opening 66(Figures 3 and 8) which is formed with a valve seat 61 and opens intovalve-controlled communication with the rear end of the passage 31(Figures 1 and 8) that leads to the closed end of the cylinder 35. Alongitudinal bore 68 is formed in the bottom wall 6| of the valve casing61 and receives the stem 1! of a valve 12 which is urged toward aposition closed against the valve seat by a spring 13 seating againstthe valve 12 and in a socket 14 formed in the section 40 of the housing43, as best shown in Figure 8. The outer portion of the bore 68 in thevalve casing 51 is threaded to receive an adjusting screw 16, theadjustment of which is retained by a lock nut 11. The valve 11, 12 isfree to slide forwardly away from the adjusting screw 16 against thetenback through the passage 61 asoama sion of the spring 16, but thedegree of closing against the seat 61 is regulated by the adjustingscrew. This valve therefore serves as means restricting the flow offluid from the cylinder 35 and through the opening 66 into the valve box56, yet the flow of fluid from the valve box through the opening 66 andinto the passage 31, and hence to the cylinderprises three cylindricalsections 66, is relatively unrestricted, since the spring 13 iscomparatively light.

The opening 66 (Figure 8) lies at the forward end of a passage II. Thispassage 6i includes an enlarged section 62 communicating directly withthe opening 66, the enlarged section 62 extending laterally inwardlytoward the central plane of the valve casing 56 and then rear-wardly, asat 66 (Figure 7). .The passage section 615 communicates with a laterallyextending passage section 65 (Figure 7) which at the left side of thecasing 51 (right side as viewed in Figure 3), opens into communicationwith a passage section 66 (Figure substantially directly behind, but notin communication with, the opening 62 in the high pressure passage 63.The passage section 66 communicates upwardly through an opening 61having a valve seat with which a valve 68 cooperates, into communicationwith a branch passage 69, which is generally U-shaped as shown in Figure5.

Referring again toFigure 5,v it will be seen that the upper portion ofthe high pressure passage and theupper and forwardly extending portion89a of the branch passage 69 open into communication with a verticallyextending control valve bore indicated in its entirety by the referencenumeral 9i. This control valve bore 9I is formed in a thickened section,indicated at 92. of the rearand adjacent side wall of the valve housing51. The valve member operating in the valve bore 9| is indicated in itsentirety by the reference numeral 95 and includes an upper cylindricalsection 96, an intermediate cylindrical secvertical cates with a'passage extension 16 H6, Iii and H8 connected together by necks orshanks H9 and I2 I. Preferably, the valves 95 and I 115 are identical tofacilitate their manufacture.

Referring now to Figure 5, a passageway I25 opens into the high pressurepassage 63 and intersects the main control valve bore 98, extendingrearwardly and opening into communication witha'cross bore I26 disposedparallel with the upper cross bore I04 and formed in thethickened-casingpection I05 (Figures 7 and 8). At the right side of thevalve box, left sideas viewed in Figure 3. the cross bore 526 communi-$2? that intersects the auxiliary valve bore 001. Normally, the passagesi25 and i211 are closed by the cylindrical sections 91 and ill of themain and auxtion 91, and a lower. cylindrical section-96, connected bynarrow necks or'shanks IN and- I02.

The upper portion of thehigh pressure passage 66 opens into the upperpart of the control valve bore 9I, and the high pressure passage 69 isextended rearwardly past the bore 9|. as at I06 (Figure 2).andcommunicates with a cross passage I04 that extends transversely-ofthe valve box, being formed in a thickened transverse section I06(Figures 7 and 8) thereof. The control valve bore 9I (Figure 5) justreferred to lies at the left side of the valve box 66 (right side as.

viewed in Figure 3), and at the other side of the valve box the crosspassage I64 extends forwardly, as at I06 (Figure 6), and opens intocommunication with a second control valve bore I01 formed in a thickenedsection I06 of the valve box and which, in constructional arrangement,is

substantially like the control valve bore '9I described above. Thecontrol valve bores 9I and I01 are disposed vertically and substantiallyin parallelism, and the passage section I06, extending forwardly fromthe end of the cross passage I04 (IiIgure 6), communicates through anopening III (Figures 3 and. 6) into the interior of'the valve casing 51andwhich may be considered as an extension 66' of the sump 66 (Figure 1)in that fluid discharged from the valve bores 6| and I61 flows out intothe interior of the-casing 51 and thence into the sump proper, indicatedat 66 in Figure 1. Asecond control valve H5 is disposed in a verticalposition in the bore I01 (Fig-' ure 6) and, like the valve 66 describedabove, comvalve bore I0'i and a lower extension i266 opening intocommunication with an outlet chamber #136 through a valve controlledopening I35 in which a valve I36 is disposed. The valve 86 (Figure 5)and the valve I36 (Figure 6) are substantially. identical, each having astem extending up-. wardly through a suitably formed openingin the bodyof the valve housing so that both valves may-be operated by downwardmovement of the valves and H5, respectively. The opening for the stem ofthe valve 68 is indicated at I36 in Figure5, and the opening for thestem of the valve I66 is shown at I69 in Figure 6. These openings fitthe valve stems closely so as to be substantially leak-tight. The outletchamber I 64 is closed at its lower end by a screw-threaded plug I4I,between which and'the valve I36 is a spring I42. The outlet chamber I34communi-' in Figure 6, there is an open space I5I around the upper endof the stem ofthe valve I66 and below the end I I6 of the valve I I5,the open space -,I6l communicating with the reservoir 63'. A leakopening I62 connects the branch passage. I3I

with the space or opening I5I, and flow through the leak opening I52 iscontrolled by a needle valve I54 held in any position of adjustment by alock nut I55. As best shown in Figure 5, a similar needle valve I51controls a leak opening I56 extending between the branch passage 69 andan open space I59 that lies between the lower end 96 of the valve 95 andthe upper end of the stem of valve 66, the space I59 opening-.laterallyinto direct communication with the reservoir 36', as best shown inFigures 7 and 8. A look nut I6I holds the needle valve I51 in anyposition of adjustment. Normally, the controlled flow through the leakopenings I52 and I56 into the reservoir 63' is relatively small.

The valve operating linkage and control mechanism therefor will now bedescribed. Briefly,

the main valve 95 is so controlled as tobe movable manually into aposition causing'fiuid to be directed under pressureinto the forward endof the cylinder 65, with suitable means interconnected with the pistonfor automatically return- .ing the main valve 95 me neutral positionwhen the piston is fully extended. A lug I10 (Figures 3 and 8) on theinside of the casing 51 forms a stop against which the arm 42 or link 89may engage if the valve return means should not function. The valve 85is also automatically controlled, preferably through the arm I42 andlink -58, for automatically returning the main valve with suitablespring means for automatically re .turning the same to a neutralposition after it has been moved in either a raising or loweringdirection out of a neutral position.

Referring now more particularly to Figures 3 and 9,.the upper'portion ofthe valve case has itsside walls apertured, as at "I and I12, toreceivegportions of the valve control mechanism. The right-hand sidewall aperture I1I receives'a tubular shaft member I15 which extendsthrough the casing wall and at its outer end has welded or otherwisesecured thereto a hub member I16 to which an operating handled] 11 issecured. The inner end of the tubular shaft I15 is splined and receivesa two-armed member 019 (Figure 4), one arm I8I ofwhich has an extensionI82 and the other arm I83 of which is formed with a split section I84adapted to be clamped about the'shaft I15 by a clamping cap screw I85.Both of the arms I8I and Hit carry pivot pins I81 and I88',respectively, which are received in the arm portions I SI and I92 ofayoke member I 89. The arms I9I and I92 are slotted in an arcuatedirection about the axis of the tubular shaft 1115,

whereby either pin I81 or i823 may move downwardly without moving theyoke use, but upward movement of either pin will raise the yoke,

The latter is secured to a vertical rod l95 that is disposed verticallyin the valve case 51 and at its lower end receives a biasing spring 596and at its upper end passes through the bifurcated lug I91,

the bifurcation or slot receiving the pin 695 being indicated by thereference numeral I98 in Figures 3 and 6. The lug le'l as best shown inFigure has a socket let in which the upper end of the spring I 96 isplaced. The spring B96 is normally under initial compression when thelower end is connected to the pin or rod I95, and hence the seating ofthe upper end of the spring I96 in the socket I99 serves to hold theassociated parts in position. The arm it! (Figure 4) of the member I19,is connected by a link member 20I, preferably formed of two links 202and.

203, to the upper end of the valve II5, as by a pivot pin 204.Preferably, the upper end of the valve H5 is provided with a flattenedextension 205 to receive the lower end of the link connec- 'tion 2!. Asbest shown in Figure 6. an adjusting screw 2% is mounted in a threadedopening 209 in the upper wall of the case 51 so that its lower end is ina position to serve as a stop for the lever arrn 583, thus limiting themovement of the valve operating member I8I in one direction. Movement ofthe member I8I in the other direction is limited by the engagement ofthe lever arm extension I82 (Figure 6) with an abutment section 2Mformed on the inner surface of the valve case adjacent the junction ofthe upper and rear walls.

Referring again to Figure 9, the tubular shaft I15 includes a socket 2I5in which one end of shaft 2I1 receives the other end and major portionof the shaft 2 I6 and is disposed for rocking movement in the casingwall opening I12. A main valve operating member, indicated in itsentirety by the reference numeral 228, is secured to the tubular shaft2I1 adjacent the left side wall of the valve case 51 (right side asviewed in Figures 3 and 9). The valve operating member 22B is s'plinedto receive the splined exterior portion of the tubular shaft 2" and isbifurcated, as at 222 (Figure 5), and provided with a clamping cap screw223 for attachment to the tubular shaft 2I1. The member 220 includes anarm 225 that extends rearwardly (Figure 5) and is connected by a linkmember 226 with the upper flattened end 221 of the main valve 95.Preferably, the link member comprises a pair of links or straps 228 and229 (Figures 3 and 9), the upper ends of which are apertured to receivea pivot pin 23I, and the links 228 and 229 are similarly apertured attheir lower ends to receive a pivot pin 232 by which they are connectedto the upper end 221 of the, valve 95. An extension 235 is formed on thearm 225 and is adapted to engage a boss 236 formed on the valve case 51(Figure 5), whereby the clockwise rocking movement of the valveoperating member 228 is limited. The valve case 51 has a bored extension288 receiving a detent spring 238 which acts against a vided with threenotches 242 into any one of which the ball 2 is adapted to seat. Theouter or forward end of the spring 239 acts against a screw plug 263threaded into the outer or forward end of the bore in the casing part238. Rocking the tubular shaft 2I1 in one direction or the other fromthe intermediate position, Figure 5, serves to raise or lower the valvemember 95, the ball 2M seating in either the upper or the lower notch242.

The tubular shaft 2H and the valve operating arm 220 secured thereto areadapted to be rocked in one direction or the other by a hand leverindicated in Figures 9, l0 and 11 in its entirety by the referencenumeral 258. The hand lever 256 includes a hub member 25: secured, as bywelding 252 (Figure 9) or any other suitable means, to the end of thetubular shaft 281 that extends laterally outwardly of the valve case 51.The member 25l has secured thereto or formed integral therewith a shanksection 254 which has a. portion slabbed away, as at 255 in Figure 11,and an upwardly and laterally outwardly angled threaded portion 286. Asleeve 251 having internal threads is adjustably mounted on the threadedportion 256 of the shank 252, and a rod or shaft 258 is secured to theupper end of the sleeve 251 and at its upper end carries a knob 258, Theshank 254 has an extension 26I of reduced diameter seating in a socketsection 262 formed in the upper portion of the sleeve 251. Turning theknob 259 therefore turns the sleeve 251 and screws the same downwardlyor upwardly along the shank 254. For the purpose of yieldably holdingthe sleeve 251 in any position of adjustment, it is provided with aplurality of longitudinal internal grooves 265 and the shank 254 isprovided with a detent ball 266 urged outwardly by a spring 261 seatingin a cross bore cated. in its entirety by the reference numeral 215 inFigure 8, is adapted to connect the shaft 218 (Figure 9) with the arm 42that moves with the piston 38 (Figure 1) The continuous control linkage215 includes an arm 218 Figures 8 and 9) fixed to the shaft 218 adjacentthe laterally inner end of the tubular shaft 211 in any suitable manner,preferably by a set screw 211 (Figure 8) having an inner end 218 thatseats in a slot 219 (Figure 9) formed. in the shaft 2l6, whereby the arm218 is'heid against movement relative tome shaft 218. The outer end ofthe arm 218 is connected by a pivot pin 28! to a pair of links 282 whichat their lower ends are connected by a pivot pin 283 toone arm 284 of abell crank 285. The other arm 288 of the bell crank 285 is connected bya link 281 with a lift shaft arm 42, as best shown in Figures 1 and 8.By virtue of the linkage 215 just described, increments of movement ofthe arm 42 will cause corresponding increments of movement of the shaft2l8 and the cam or stop section 213 (Figures 9-11) The bell crank 285 ismounted on a shaft 28! which, as best shown in Figure 3, has one endmounted in the right side wall of the casing 51 and the other endmounted in 2. lug 292 which is secured to or forms a, part of thethickened section 188 (Figure 8) of the valve case 51. As best shown inFigure 3, the portion of the supporting shaft 295 that seats in the lug292 is of smaller diameter than the other portion, thereby providing ashoulder against which one side of the bell crank 285 abuts.

It may be mentioned at this point, although more detailed reference willbe made below when the operation of the mechanism is described, thatwith the piston 38 in a rear position, in which the tools are lifted,when the handle 258 is moved rearwardly, in a counterclockwise directionas viewed in Figures and 8, the main valve 95 is disposed in a positionto cause fluid to be released from the cylinder 35 and will flow throughpassages 38, 31, 88 and sump. The consequent forward movement of isreturned to neutral position is determined by the position of adjustmentof the sleeve 251' on the shank 254, the return of the valve to neutralposition taking place after a greater movement of the piston'38when thesleeve 251 has been unscrewed upwardly than is the case when the sleeve251 is screwed downwardly toward the stop member 213. Thus, the positionof the handle 258 on the arm to'which the tools are automaticallylowered.

To limit the outward movement of the piston 38 in the tool-raisingdirection, I provide an end return linkage, indicated in. its entiretyby the reference numeral 388 in Figure 7, and operative to return themain valve 95 to a neutral position when the piston 38 reaches the endof its ,outward or rearward movement, entirely irrespective of theposition 'of the lowering control linkage 215 and associated parts.Referring now more particularly to Figures 3 and 7, a bell crank 38l ismounted tor rocking movement on the shaft 29! in a position (see Figure3) between the bell, crank'285 and the lug 292. One arm 382 of the bellcrank 38! is disposed in a position in the path of movement of the rearend of the link or rod 39 connecting the piston 38 with the lift shaftarm 42. The other arm 383 of the bellcrank 381 is apertured at 384 toreceive a pin 385, which has a head 386 at the opposite end thereof. Thehead 388.is pivoted, as at 381, to an arm 388 which is slotted hub 389,drawn into rigid clamping engagement with the tubular control rockshaft211.

by means of a clamping bolt 3| l. The pin 385 is freely slidable throughthe aperture 384 in the arm 383 and'a coil spring 3l3 is coaxiallydisposed around the pin 385 between the arm 383 and the head 388,against which the opposite ends of the spring 3l3 bear, respectively. Apin 314 retains the pin 385 within the aperture 384. The spring 313 andpin or rod 385 thus serve as a compressible connection between thepistonactuated bell crank 38! and the member 389 that rocks the valvecontrolling tubular shaft 211.

Referring to Figures 3 and 5, it will be remembered that the passage-63opens into communication through the opening 82 with the duct 34(Figure 1) leading to the high pressure side of the pump 25. A highpressure relief valve is provided for automatically openingcommunication between the high pressure passage 83 and the sump 33 inthe valve box 58 in the event that for any reason the pressure in theI59 back to the i the arm 42 permits the rockshaft I8 to rock in acounterclockwise, direction. (Figure 1)) which movement is normallyutilized in farm implements for lowering tools or the like to operatingposition. As the arm 42 continues to rock in a counterclockwisedirection (Figure 1), the link 281 is shifted forwardly and causes thebell crank 285 (Figure 8) to be rocked in a clockwise direction androcks the arm 218 and shaft 218 in a clockwise direction. This movementof. the shaft 2l8 serves to swing the cam or stop section 213 forwardly,or in a counterclockwise direction as viewed in Figure 10. As the piston38 continues to move forwardly, the cam or stop section 213 will moveinto engagement with the lower end of the sleeve 251, a slightadditional movement after engagement serving to return the valve controlhandle restoring the valve 95 (Figure 5) to its neutral position, asshown. The point at which the valve 258 to a neutral position,

pump and high pressure passages rises to an abnormal degree. The reliefvalve is indicated in Figure 3 by the reference numeral 328 and isnormally held in closed position against the seat 321 formed around anopening in one wall of the passage 83 leading directly to the sump 33 bya relatively heavy spring 324. The sprin 324 extends transversely acrossthe lower portion of the valve box and at its outer end bears against anadjusting plug 325 screwed into a suitably formed opening in the sidewall of the case 51. As best shown in the valve 328, which is indicatedat 328, extends into a blind guide opening 321 formed in the oppositewall of the passage 83, the stem 328 having suitable ducts formedtherein to permit the valve 328 to be moved outwardly away from theopening 321 in the event an overload occurs. The relief ducts in thestem 328, permitting the oil to flow into and out of be noted that thepressure exerted by the relief 254 adjusts the position integrallyformed with a Figure 3, the stem of the blind opening 321. are indicatedat 328 in Figures-3 and 5. It will spring 324 may be'adjusted fromoutside the valve case 51.

The operation of my new and improved hydraulic control power liftmechanism is substantially as-follows.

The pump gears30 and 31 (Figure 1) rotate at all times that the tractormotor is in operation and the power take-off shaft 22 is rotating.

Substantially incompressible fluid, preferably oil, normally fills theentire system, and is continually delivered by the pump 25 upwardlythrough the passage 34 (Figure 1) through the opening 62 (Figure 5) intothe high pressure passage 63. If the pressure does not exceed that forwhich the relief valve 320 is set, the latter remains closed, andtherefore the oil flows upwardly through the passage 63 around the neck101 of the valve 95 and into the cross bore I04. From there the oilflows from the cross bore 104 into the passage 106 (Figure 6) andaroundthe neck 119 of the valve 115, and thence outwardly through .the opening111 into the sump 33 which,

as mentioned above, forms a part of the reservoir or sump indicated inFigure 1 by the reference numeral 33 from which oil is drawn into thepump 25. When the two valves 95 and 115 are in the positions shown inFigures 5 and 6, the pump 25 idles, since the oil flow is not performingany work.

When the piston 38 is disposed at the forward end of the cylinder 35,almost all of the oil has been discharged from the cylinder 35 anddisposed in the sump 33, and this is the normal position of the pistonwhen the tools are in a lowered or operating position. In this position,the cam or stop section 213 (Figure is disposed in em gagement with thesleeve 251, having previously engaged the latter and returned the handlever 250 from a rearward position to an upright or neutral position, asshown in Figure 10. Assume now that it is desired to raise the tools.The operator grasps the handle knob 259 and swings the handle 250forwardly, or in a clockwise direction as viewed in Figures 1 and 5-8.This rocks the tubular control shaft 211 in a corresponding direction,which, acting through the arm 225 and link 223, moves the main valve 95upwardly out of its neutral position (Figure 5) into an upper position,the detent ball 241 resting in the lower notch 242. In this position ofthe valve 95, the intermediate cylindrical section 91 closes off thecommunication between the upper end of the pressure passage 63 and thecross bore 104 but-opens communication between the high pressure passageI25 and the upper portion 89a of the branch passage 89 through theopening 125, the oil under pressure flowing through the latter anddownwardly about the narrowed neck or shank 102 of the valve and intothe upper end of the branch passage. The oil under pressure flowsdownwardly through the branch passage 39 (Figure 5) and into the lowerportion thereof and past the check valve 88 into the chamber 88. Acertain amount of oil is by-passed through the leakage opening 158, theamount depending upon the adjustment of the valve 151. From the chamber86 below the valve 88 the oil flows laterally inwardly and upwardly andinto the passageway 85 (Figure '1), and then forwardly through thepassage 84 and into the outlet chamber 82 (Figures 7 and 8) from whichthe oil flows through the opening 66 past the valve 12 and into thepassage 31 leading into the passage 36 (Figure 1) that communicates withthe closed end of the cylinder 35. It will be noted that in this 12position of the valve 95 (Figure 5) the cylindrical section 91 closesoff communication between the high pressure passage 63 and the crossbore 104, but the lower cross bore 126 is still in communication,through the opening 125, with the high pressure passage.63. However, atits other end the cross bore 126, as best shown in Figure 6, is closedby the cylindrical section I 11 of the valve 115, the latter normallybeing in its neutral or intermediate position, as shown in Figure 6.

Thus, through the path just described, when the operator moves thehandle 258 forwardly, oil is directedunder pressure into the cylinder35, forcing the piston 33 therein rearwardly and swinging the rockshaftI8 and arm 42 in a clockwise direction (Flgure 1). This movement of thearm 42 acts through the linkage 215 (Figure 8) to rock the shaft 216 ina counterclockwise direction-(Figure 8) which swings the cam or stopsection 213 rearwardly into its dotted line position, Figure 10, awayfrom the sleeve 251.

As the piston moves outwardly to its terminal position, the rear end ofthe connecting rod 39 engages the arm 302 (Figures 7 and 8) swinging thesame in a clockwise direction as viewed in Figure 7, compressing thespring 313 between the arm 303 and the head 306, the detent ball 241,being seated in the lower notch 242 (Figure 5) serving to hold thecontrol rockshaft 211 against movement until the spring 313 has beencompressed by the continued movement of the piston and bell crank 301until the coils of the spring are in solid contact with each other.Further movement of the piston rod 39 against the bell crank 301 and itsarm 302 forces the control rockshaft 211 to move in a counterclockwisedirection (Figures 5 and 7) until the ball 251 (Figure 5) is unseatedfrom the lower detent notch 242. The valve 95 is then free to slidewithin the valve bore 91, and the energy stored in the spring 313quickly slides the valve element 95 into the neutral or holding position(Figure 5) in which the ball 241 seats in the intermediate notch 242, asshown. The oil under pressure in the cylinder 35, holding the piston 38in extended position is hydraulically locked against returning to thesump 33 by virtue of the seating of the check valve 88, and as the valve95 is returned to neutral position, the downward movement of thecylindrical section 91 (Figure 5) of the valve opens communicationbetween the high pressure passage 83 and the upper cross passage 103,the oil then flowing freely through the cross section 183 and outwardlythrough the passage 185 (Figure 6) and the opening I 11 into the sump33'.

Assume, next, that with the tools in raised position and, as described,with the piston 38 moving the hand lever 250 hydraulically locked in itsextended or rearward position, the operator now desires to return thetools to their lowered position. This is done by rearwardly from itsupright or neutral position in a counter-clockwise direction (Figure 5)which moves the valve downwardly into a position with the detent 231engaging the upper notch 242 and with the lower end of the valve 95engaging the upper end of the stem of the check valve 88, opening thelatter and permitting the oil in the cylinder 35 to flow rearwardlythrough the passages 38 and 31 past the partially open valve 12 and intothe passage 81 which, as described above, leads into the chamber 86. Oilfrom the latter zone passes through the open valve 88 and through thebranch passage 89 and through the lower end of the valve bore 91 aroundthe neck or shank I02 ,handle I11 raise the valve H5.

13 a valve and into the opening I59 leading directly into the sump 33'.The rate of lowerin of the tools depends upon the adjustment of thevalve'12 (Figure 8) As the tools lower, usually under the action ofgravity, the rockshaft18 (Figure l) rocks in a counterclockwisedirection, causing the piston 38 to be moved forwardly. As the arm 42 onthe rockshaft I8 swings in a counterclockwise direction, a pull isexerted through the link 281, rocking the bell crank 285 in a clockwisedirection (Figure 8) and swinging the arm 216 and the shaft 2I6 in aclockwise direction, counterclockwise as viewed in Figure 10. Thus, asthe tools move downwardly to their lowered position the correspondingmovement of the shaft 2I8 swings the cam or stop section 213 (Figure 10)forwardly, ultimately engaging the lower end of the sleeve 251 lever 258forwardly, restoring it to its neutral position, which movement actsthrough the tubular rockshaft 2I'1 (Figures and 9) to lift the valve 95into its neutral position, which permits the valve 88 to close,

or the that the position of adjustment of the sleeve 251 on the threadedshank 254 determines the point at which the tools will automatically belocked in a lowered position. To have the .tools move to a relativelyshallow operating position, the sleeve 251 should be screwed downwardlyon the shank at the right side of the valve box 58 and, as best shown inFigure 9, is directly connected to the shaft I15 on which the arm I8I(Figure 4) is mounted, the arm I8I being connected through the link 203with the valve forwardly (counterclockwise as viewed in Figure 4) actsthrough the links 203 to The action of the valve, so far as the controlof the fluid is concerned, is substantially like the valve 95. Theupward movement of the valve II5 (Figure 6) closes the opening I I Ithrough which the oil from the high pressure passages normally flowsinto the sump 33'. When the opening Hl is closed, the oilis forced toflow from the high pressure passage 63 through the opening I25 andaround the annular groove i25a (Figure 5) into the cross passage 326.Since the valve H5 (Figure 6) is in an upper position, the lower edge ofthe intermediate cylindrical section II1 lies adjacent the upper edge ofthe opening I21. Hence, oil under pressure flows downwardly around thevalve I I5 and through the passage extension I32 into the branch passageI3l. From thence the oil flows downwardly through the opening I35, pastthe valve I35, and into the outlet chamber 43d. As best shown in Figure3, from this point the oil under pressure flows outwardly through theopening I43 and the connection I48 into the hose I41 that leads to theram unit 50. As shown in Figure 6, a certain amount of oil passesthrough the leak opening I52 into the sump 33, the action being the sameas for the leak opening I58 (Figure 5). The pump 25 (Figure 1) being ofthe positive displacementtype, and the shaft 22 normally being driven ata substantially constant rate, it will be seen that the time ofoperation of the ram units 50' and 5I will depend only upon II5.Swinging the i4 their respective effective volumes. To secure themaximum in speed of operation, the leak passages I52 and I58 will beentirely closed, but if and moving the hand thus preventing further flowof fluid from the cylinder 35. It will thus be seen edge of the sleeve251 earlier in the cycle than :passage I3 I,

somewhat slower action is desired, the valves I51 and I54 will beopened, the greater the amount of opening the slower the operation ofthe associated ram unit.

It is to be understood that the ram unit 58, being connected by a.flexible hose I41 with the valve box 58, may be disposed in any suitablelocation on the implement, depending upon the function it is to serve.Usually, it is so connected with tools or other parts .as to shift themagainst a force, such as their own weight, in which case when the handleI11 is moved in the other direction to permit the oil from the ram unit50 to flow back into the sump, the weight of the tools and associatedparts is sufllcient to force the oil at an acceptably rapid rate backinto the reservoir. If the weight of the tools is not available or isnot adequate, springs 330 may be utilized, being diagrammatically shownin Figure 3, for retracting the piston member 33I of the ram unit 50.

, When it is desired to permit the ram unit 50 to retract, as forlowering the tools, the handle I11 is swung rearwardly, clockwise asviewed in Figure 4. This moves the valve 5 (Figure 6) downwardly,forcing the check valve I35 to open I the stem I2I of the valve H5 andout into the reservoir through the opening or space I5I. The action ofthe yoke I89 and associated spring mechanism tendingto hold the valve H5and handle I11 in neutral position, has been described above. Oil may beadded to the system from time to time as desired by removing one or bothof the filter plugs F valve box.

While I have shown and described above -the preferred structure in whichthe principles of the present invention have been incorporated, it is tobe understood that myinvention is not to be limited to the particulardetails shown and described above, but that, in fact, widely diiferentmeans may be employed in the practice of the broader aspects of myinvention.

What I claim, therefore, and desire to secure by Letters Patent is:

the neck I2I of .1. A power lift mechanism for tractors and the likehaving a source of fluid pressure, comprising a cylinder closed, atoneend and open at the other, a piston and piston rod movable therein,fluid connections leading from said source, to the closed end of saidcylinder and including a control box mounted adjacent the open end ofsaid cylinder and movable valve means in said box, 'a rockshaftjournaled in said control box. I

and operatively connected with said valve means for shifting the latter,releasable detent means retaining said valve means in a position inwhich fluid is directed to the closed end of said cylinder, controlmeans outside said box and operatively connected with said rockshaft, abell crank rockably mounted in said control box adjacent said rockshaftand having one arm disposed in the path of movement of the outer end ofsaid piston rod, and resiliently yieldable means connecting the otherarm of said bell crank with said rockshaft, whereby movement ofsaid'piston to a given position acts through said bell crank, saidyieldable means, and said rockshaft to overcome said- I32 and thendownwardly around. I

in the upper wall of the being shiftable between open and l detent meansand to shift said valve means into a position cutting off flow of fluidto the closed end of said cylinder.

2. Control mechanism for a hydraulic actuated device including acylinder and a movable piston member therein, om rising a valve box saidcylinder and valve box each having an open end and ing a movable valvethe open end of the valve box facing the open' ing a part adapted in onepositionto extend out of the open end of the cylinder and into aposition adjacent the open end of'said valve box. a valve element insaid valve box and shiftable between open and closed positions, 'meansin said valve box for yieldably retaining 'said element in one of saidpositions, means in said valve box including a bell crank rockablymounted in said valve box adjacent said valve element and having one armdisposed adjacent said opening in the path of movement of said pistonmember in a position to be engaged by said piston member when the latterreaches a predetermined position for moving said valve element to theother of said positions, the other arm of said bell crank beingconnected with'said valve member by means including a spring fortransmitting force therebetween to insure a complete movement of saidelement from one position to the other.

3. Control mechanism for a hydraulic actuated device including acylinder and a movable piston member therein, comprising a valve boxdisposed adjacent one end of said cylinder, a ductin said valve box forsupplying hydraulic fluid to said device, a valve element movable acrosssaid duct for controlling said fluid supply, said element closedpositions relative to said supply duct, detent means carried by saidvalve box, for yie'ldably retaining said element in said open positionin which fluid is supplied to said device to move said piston memher, ashaft journaled in said valve box, linkage means connecting said pistonand said shaft whereby the latter moves concomitantly with the piston, atubular shaft supported at least in part on said first shaft andoperatively connected with said valve element, a manually actuated levermounted on said tubular shaft, the end of the latter and the adjacentend of said first shaft extending outside said valve box and saidmanually actuated lever being also outside said valve box, means forautomatically shifting said elementfrom open to closed position to stopsaid piston member when it reaches a predetermined terminal position,comprising a part engageable by said piston member, an arm fixed to saidtubular shaft, and a spring interconnecting said part and said arm andadapted to be stressed by movement of said part caused by motion of saidmember in one direction, to insure completion of said movement of saidvalve element into full closed position after the latter has beendisengaged from said detent, a second part adjustably mounted on saidmanually actuated lever, and means on the outer end of said first shaftengageable with said adjustable part and acting through the lever andtubular shaft for also shifting said element from open to closedposition to stop said piston member when the latter moves in theopposite direction and reaches a position determined by the position ofsaid adjustable part on said lever.

4. Hydraulic mechanism comprising a single source of fluid pressure, apair of separately movable cylinder and piston units, a valve box havingtwo sets of valve-controlled passages, each haw end of said cylinder,said piston member includtherein, and a high pressure with said sourceof fluid presto said valve controlled pas Passage connected sure andleading sages, separate passages leading respectively,

from said valve controlled passages to said cylinder and piston units, ashaft journaled in said valve box at one side thereof and operativelyconnected with one of said movable valves, a tubular shaft journaled insaid valve box at the other side thereof and operatively connected withthe other of said movable valves, a control shaft supported at one endon said first shaft and at the other end in said tubularshaft, meansconnecting said control shaft with the piston of the associated cylinderand piston unit so as to move said control shaft concomitantly with saidan adjustable connection between piston, and i said control shaft andsaid tubular shaft whereby to terminate the flow of fluid from saidsource to said cylinder and piston unit when the piston in the latterunit has moved an amount, depending on the adjustment of said adjustableconnection.

5. Control mechanism for a hydraulically operated device that includestwo piston and cylinder units respectively connected with parts to beactuated, said mechanism including a valve. box, a tubular shaftjournaled in one wall of said valve box, a second shaft journaled in theopposite wall of said valve box, said shafts being in alignment, a thirdshaft extending through said tubular shaft and socketed in said secondshaft, means connecting the latter with control valve means for one ofsaid units for controlling the same independently of the other unit,means connecting said tubular shaft with control valve means for saidother unit for'controlling the latter, two.

means for operating said control valve means for said other unit, oneconnected to the outer end of said tubular shaft and the other connectedto the inner end of said third shaft, and means at the outer end of saidthird shaft for operating said tubular shaft.

6. Control mechanism for a hydraulically operated device that includestwo piston and cylinder units respectively connected with parts to beactuated, said mechanism including a valve box, a

tubular shaft journaled in one wall of said valve box, a second shaftjournaled in the opposite wall of said valve box, said shafts being inalignment, a third shaft extending through said tubular shaft andsocketed in said second shaft, means connecting the latter with controlvalve means for one of said units for controlling the same independentlyof the other unit, means connecting said tubular shaft with controlvalve means for said other unit for controlling the latter, an operatingpart including a threaded member secured to the outer end of saidtubular shaft, a handle comprising a part adjustable on said threadedmember, a cam member on the outer end of said third shaft disposed in aposition to engage and move said adjustable part for actuating saidtubular shaft and said control valve means for the associated piston andcylinder unit, and means movable with the part actuated by said lastmentioned unit for rocking said third shaft and acting through said cammember and tubular shaft for controlling said last mentioned unit.

7. Hydraulic mechanism comprising a casing having a valve passage,'avalve member slidable therein and comprising a pair of spaced closuresections connectedby a neck of reduced diameter,

said valve passage having a high pressure inlet intersecting saidpassage adjacent one end of the latter, theopposite end of said passageserving as 17 an exhaust opening, said valve member being normally sopositioned that one of said closure sections blocks said inlet and theother section is positioned adjacent said opposite end of the passage,said casing having an outlet duct intersecting the intermediate portionof said valve I passage and extending to a check valve seat disposedsubstantially coaxially of said valve passage in said casing beyond saidexhaust opening, a spring biased check valve covering said seat, saidcheck valve having a stem extending through the casing wall formingsaid- 'outlet 'duct and terminating adjacent theend of said valvemember,

provided with an exhaust. port, and an adjustable valve in said port foradjusting the amount of opening to provide for bleeding a portion of thefluid supplied to said outlet port.

9. Hydraulic mechanism comprising a casing having a, reservoir and apair of valve passages, a valve member slidable in each of saidpassages, each of said members comprising a pair of spaced closuresections connected by a neck of reduced diameter, each of said valvepassages having a high pressure inlet intersecting it adjacent one endthereof and a common by-pass intersecting said passages and connectedwith said reservoir, the other end of each valve passage serving as anexhaust opening and connected with the reservoir, each of said valvemembers being normally so positioned that one of said closure sectionsblocks said inlet and the other section is positioned adjacent saidopposite end of the passage, said casing having a pair of outlet ductsintersecting the intermediate portions of said valve passages,respectively, each duct having a check valve seat disposed substantiallycoaxial of the associated valve passage in said casing beyond saidexhaust opening, spring biased check valves covering said seats,respectively, and having stems extending through the casing wall formingsaid outlet ducts and terminating adjacent the ends of the associatedvalve members, and means for independently shifting each of said valvemembers in one direction from said normal position to keep said inletclosed, open said exhaust openings and said by-pass and engage saidcheck valve stems to open said check valves, and in the other directionto close said exhaust openings and said by-pass and to connect saidinlet to said outlet ducts.

10, Hydraulic mechanism comprising a cylinder, a piston movable therein,a part connected to said piston for transmitting force therefrom, asource of fluid pressure, fluid connections leading selectively, an armconnected with said one shaft and engageable by said piston connectedpartfor returning said shaft to said neutral position to interrupt theflow of fluid to said cylinder when the piston moves to a predeterminedpoint in one direction, an arm connected with the other of said shafts,means connecting said last mentioned arm with said piston connected partfor rocking said other shaft by movement of said piston, and anadjustable device connecting said coaxial shafts for returning saidvalve-connected shaft to said neutral position when the piston moves toa predetermined point in the other direction to stop the piston.

11. Hydraulic mechanism comprising a casing, a cylinder associatedtherewith, a piston movable in said cylinder and having a forcetransmitting part connected thereto and extending into said casing. apower transmitting rockshaft mounted in said casing and connected tosaid part, a source of fluid pressure, fluid connections in said casingleading from said source to said cylinder and including a valve passageand a control valve slidable therein in relatively opposite directionsfrom a neutral position to cause said piston to move toward either endof said cylinder, respectively, spring biased detent means engagi-ngsaid valve for yieldably holding the latter in adjusted position, andcontrolmechanism for said valve comprising a tubular shaft journaled insaid casing, an inner shaft journaled coaxially within said tubularshaft, an arm on one of said shafts swingably connected to said valvefor shifting the latter responsive to rocking movement of said shaft, acrank arm disposed in the casing in -the path of movement of said pistonconnected part, a spring connecting said crank arm to said one shaft andadapted to be stressed when the piston connected part engages said crankarm at a predetermined point in its movement in one direction, saidspring therebylovercoming said detent and shifting said valve to saidneutral position, an arm fixed to the other of said shafts within saidcasing and connected with said piston to rock said shaft by movement ofthe piston,

said coaxial shafts extending out of said casing through a suitableopening, said one shaft having a hand lever mounted thereon outside saidcasing for rocking the shaft to control said piston, and an adjustabledevice comprising a one-way connection between said coaxial shafts.engageable responsive to movement of the piston to a predetermined pointin its movement in the opposite from said source to said cylinder andincluding tubular shaft and an inner directions responsive to directionfor returning said valve to neutral position to stop said piston.

12. Hydraulic mechanism comprising a casing, a cylinder associatedtherewith, a piston movable in said cylinder and having a forcetransmitting part connected thereto and extending into said casing, apower transmitting rockshaft mounted in said casing and connected tosaid part, a source of fluid pressure, fluid connections in said casingleading from said source to said cylinder and including a valve passageand a control valve slidable therein in relatively opposite directionsfrom a neutral position to cause said piston to move toward either endof said cylinder, respectively, spring biased detent means engaging saidvalve ior'yieldably holding the latter in adjusted position, a secondvalve passage in said casing and a valve slidably disposed therein, saidvalves being disposed vertically at opposite sides of said casing, fluidconnections between said second valve passage and said source and to asecond cylinder, and control mechanism for said valves comprisgageableby said piston connected part when the piston reaches a predeterminedpoint in its movement in one direction, a spring connecting said crankarm to the tubular control shaft associated with the first mentionedcylinder and adapted to be stressed when said piston connected partengages said crank arm thereby overcoming said detent and shifting saidvalve to said neutral position, an inner shaft journaled at oppositeends, respectively, in said laterally spaced tubular shafts andextending laterally outwardly through one of said tubular shafts, an armfixed to said inner shaft between the spaced inner ends of said tubularshafts and connected. with said piston connected part to be rockedthereby, and an adjustable one-way connection between the outer ends ofsaid tubular and inner shafts engageable responsive to movement of thepiston to a predetermined point in its movement in the oppositedirection for returning the valve to neutral position to stop saidpiston.

13; Hydraulic mechanism comprising a casing,

a cylinder associated therewith, a piston movable in said cylinder andhaving a force transmitting part connected thereto and extending intosaid casing, a power, transmitting rockshaft mounted in said casing andconnected to said part, a source of fluid pressure, fluid connections insaid casing leading from said source to ,said cylinder and ineluding avalve passage and a control valve slidable therein in relativelyopposite directions from a neutral position to cause said piston to movetoward either end of said .cylinder, respectively, a secondvalve passagein said casing and a valve slidably disposed therein, said valves beingdisposed vertically at opposite sides of said casing, fluid connectionsbetween said second valve passage and said source and to a secondcylinder, and control mechanism for said valves comprising a pair ofcoaxially disposed tubular shafts spaced laterally and journaled inopposite side walls of said casing and extending outwardly thereof andhaving arms fixed thereto swingably connected with said valves,respectively, a hand lever mounted on each of said shafts outside saidcasing walls for rocking said shafts independently to shift said valvesfrom said neutral position in mounted in said casing below said tubularshafts and between said valves, a crank arm journaled on said supportingshaft and engageable by said piston connected part when the pistonreaches a predetermined point in its movement in one direction, meansconnecting said crank arm to the tubularcontrol shaft associated withthe first mentionec cylinder for rocking saidshaft when said pistonconnected part engagessaid crank arm, thereby shifting the valve tosaid'neutral position, an inner shaft journaled at opposite ends,respectively, in

said laterally spaced tubular shafts and extending laterally outwardlythrough one of said tubular shafts, an arm fixed to said inner shaftbetween the spaced inner ends of said tubular shafts, a bell crankjournaled on said supporting shaft adjacent said crank arm, link meansconnecting said bell crank with said inner shaft and with said pistonconnected part to transmit movement from the latter to rock said innershaft, and an adjustable one-way connection between the outer ends ofsaid tubular and inner shafts engageable responsive to movement of thepiston to a predetermined point in its movement in the oppositedirection for returning the valve to neutral position to stopsaidpiston.

14. A power lift mechanism for tractors and the like having a source offluid pressure, comprising a cylinder closed at one end and open at theother, a piston and piston rod movable therein, fluid connectionsleading from .said source to the closed end of said cylinder andincluding a control box mounted adjacent the open end of said cylinderand movable valve means in said box, a rockshaft journaled in saidcontrol .box and operatively connected with said'valve means forshifting the latter, releasable detent means retaining said valve meansin a position in which fluid is directed to the closed end of saidcylinder, control means outside said box and operatively connected withsaid rockshaft, a bell crank rockably mounted in said control boxadjacent said rockshaft and having one arm disposed in the path ofmovement of the outer end of said piston rod, an arm fixed to saidrockshaft and resiliently yieldable means connecting said rockshaft armwith the other arm of said bell crank, comprising a rod pivotallyconnected to one of said last mentioned arms and extending through anaperture in the other and a helical compression spring encircling saidrod and bearing at opposite ends on said arms, whereby movement of saidpiston to a given position acts through said bell crank, saidcompression spring, and said rockshaft to overeither direction,selectively, a supporting shaft I come said detent means and to shiftsaid valve means into a position cutting off, flow of fluid to theclosed end of said cylinder.

WAYNE H. WORTHINGTON.

